The present invention relates to a rotor coil for a revolving armature and the manufacturing method thereof.
In the rotor coil of a variable speed generator motor used in a pumped storage system, the strand coils extending from each of a plurality of core slots (Roebel-transposed (coil braided) coil conductors) are welded to the solid coils that form the coil end. A plurality of solid coils, provided at the coil end around the axis of the rotor, is supported and secured by tightly fastening with the binding wires that are wound around the solid coils (for example, see Japanese Patent No. 2529953).
In such a rotor coil, to prevent the coil end from being displaced in the centrifuge direction by the centrifugal force generated during the operation of a power generator, the coil end is made of solid coils of high mechanical strength and is supported and secured strongly by binding wires. On the other hand, Roebel-transposed strand coils are used in a core slot to reduce a circulating current loss. The rotor coil having this configuration therefore increases durability.